/Engine/Source/Runtime/Renderer/Public/MeshPassProcessor.h
Returns the pipeline state sort key, which can be used for sorting material draws to reduce context switches. This variant will not attempt to create a PSO if it doesn't exist yet and will just return the fallback.
uint64 GetPipelineStateSortingKey ( const [FGraphicsPipelineRenderTargetsInfo](API\Runtime\RHI\FGraphicsPipelineRenderTargetsIn-) & RenderTargetsInfo ) const